Efficient use of power is an important design objective for many contemporary electronic devices, such as personal computers, notebook or laptop computers, personal digital assistants (PDAs), portable music players and cellular telephones. By limiting the amount of power consumed by a device, benefits such as reduced heat output and prolonged battery life may be achieved.
It is known to set the value of at least one operating parameter for a power-consuming device based in part on a detected degree of activity of the device. The operating parameter may for example be a clock frequency or a particular voltage to be applied to integrated circuitry within the device. The degree of activity may be determined by periodically polling a signal reflective of the activity of the device. If the polling reveals that the device is wholly or partially idle, the clock frequency may be lowered by a predetermined amount (e.g. by applying a predetermined scaling ratio) or the voltage may be dropped to a predetermined, lower level.
In some cases, however, even the application of a lowered operating parameter value may still result in an unnecessarily high consumption of power by the device. This may occur for example when the predetermined, lowered operating parameter value was chosen to guarantee that, when the value is applied, the device can still meet a worst-case scenario of maximum demand for computational power. For instance, if the device is a graphics subsystem responsible for generating signals representing graphics for presentation on one or more displays of an electronic computing device to which it is electrically connected, the lowered operating parameter value may have been chosen to guarantee that the device would continue to operate reliably even in the situation in which the device is driving multiple displays, each being set to the highest resolution possible (multiple displays and high resolution images generally requiring higher computational power from the device). Because the worst case scenario may occur only infrequently, however, the device may in many cases be consuming more power than necessary. Power wastage may be especially high when an operating parameter value necessary to support a worst-case scenario is significantly higher than a value necessary to support a normal scenario.
An alternative power management scheme which obviates or mitigates at least some of these shortcomings would be desirable.